Apparatus for manufacturing pretensioned concrete slabs



P 17, 1968 H. L. DENNIS 3,401,438

APPARATUS FOR MANUFACTURING PRE-TENSIONED CONCRETE SLABS Filed Sept. 30, 1963 2 Sheets-Sheet l x o I. o c u a o o f J? 14 0 o o o o o 0 0 0,74

15 6 I mvsNTolg. ffozuardli. .Dezzzgzs BY %WI%TORNEYS p 1968 H. 1.. DENNIS 3,401,438

APPARATUS FOR MANUFACTURING PRE-TENSIONED CONCRETE SLABS Filed Sept. 30, 1963 2 Sheets-Sheet 2 L i I INVENTOR.

fiozaara" llDezzzgalfi' United States Patent 3,401,438 APPARATUS FOR MANUFACTURING PRE- TENSIONED CONCRETE SLABS Howard L. Dennis, Fort Lauderdale, Fla., assignor to Houdaille Industries, Inc., Buffalo, N.Y., a corporation of New York Filed Sept. 30, 1963, Ser. No. 312,707 13 Claims. (CI. 25-41) This invention relates to an improved apparatus and system for manufacturing pre-tensioned reinforced concrete slabs.

A principal object of the invention is to improve upon former apparatus for manufacturing pre-tensioned reinforced concrete slabs, by so constructing and arranging the apparatus as to prevent slippage of the reinforcing strands or wires with respect to the concrete slab.

Another object of the invention is to provide an improved form of apparatus for manufacturing pre-tensioned concrete slabs, giving a better mechanical bond between the reinforcing strands than is attained by former apparatus, by vibrating the reinforcing strands prior to compacting concrete about the strands.

A still further object of the invention is to provide an improved form of apparatus for manufacturing reinforced concrete slabs, in which the forming of the void is improved by providing individual vibrators in the void formers.

A still further object of the invention is to provide an improved form of apparatus for manufacturing pre-tensioned reinforced concrete slabs, in which the reinforcing strands are vibrated prior to the compacting of concrete thereon, in which aligned axially spaced void formers are provided for forming voids between the reinforcing strands and in which the compacting of concrete about the strands and the forming of the voids is improved by individually vibrating the void formers.

A still further object of the invention is to provide an improved form of apparatus for manufacturing concrete slabs having spaced pre-tensioned reinforcing strands extending therealong, having a series of longitudinally spaced bins pouring the slabs in layers during advance of the apparatus along the pre-tensioned strands, and having high frequency vibrator means vibrating the top strands of the reinforcing strands at the front of the machine, and giving a better mechanical bond between the reinforcing strands, in which two sets of void formers are provided rearwardly of the top strand vibrators for forming voids in the concrete in the places between the strands, and are each individually vibrated to enhance the forming of voids in the strands and to cooperate with the vibrating strands to increase the efiiciency of compacting the concrete about the strands as it is discharged from the bins.

These and other objects of the invention will appear from time to time as the following specification proceeds and with reference to the accompanying drawings where- FIGURE 1 is a diagrammatic side elevational view of an apparatus for manufacturing pre-tensioned concrete slabs, constructed in accordance with the principles of the present invention;

FIGURE 2 is a partial fragmentary diagrammatic transverse sectional view taken substantially along line IIII of FIGURE 1 and showing the advancevoid formers and vibrators carried thereby;

FIGURE 3 is a diagrammatic top plan viewof the rearward spaced void formers;

FIGURE 4 is a view in side elevation of the void formers shown in FIGURE 3;

FIGURE 5 is a plan view of the top strand vibrator;

, 3,401,438 Patented Sept. 17, 1968 "ice FIGURE 6 is a view in side elevation of the vibrator shown in FIGURE 5; and

FIGURE 7 is an end view of the vibrator shown in FIGURES 5 and 6.

In the embodiment of the invention diagrammatically illustrated in FIGURE 1 of the drawings, I have diagrammatically shown an apparatus for manufacturing pre-tensioned, reinforced concrete slabs which may be used'for roofs, walls or floors of buildings. The apparatus includes generally a frame 11, which may be supported on a gantry (not shown) on longitudinally extending beams 12, and moved along the floor by the gantry in vertically spaced relation with respect thereto, in the direction of the arrow in FIGURE 1, and along a series of parallel spaced upper and lower laterally spaced pre-tensioned wire strands 13 and 14 extending along opposite sides of a series of advance void formers 15, 15 and a second series of aligned rearwardly spaced void formers 16, 16 following the advance void formers and in direction alignment therewith. The gantry may be a four-legged gantry of a conventional construction and is no part of the present invention so need not herein be shown or described.

The frame 11 has three longitudinally spaced vertically extending bins 17, 18 and 19 supported thereon between beams 20 and 21 suitably suspended from the beams 12.

The bins 17, 18 and 19 may contain mixtures of concrete and aggregate of different consistencies. For example, the front .bin 17 is adapted to contain a mixture of cement and relatively coarse aggregate and deposit the mixture on a flat pallet 22 resting on the floor to form the bottom layer of the concrete slab. The intermediate bin 18 is adapted to contain a mixture of cement and aggregate, which may be finer than the aggregate in the front bin 17, and deposit an intermediate layer of concrete on top of the base layer deposited on the pallet 22 by the bin 12. The rear bin 19 is adapted to deposit a top or finishing layer of cement and'fine aggregate, and thereby form the finishing layer of the slab.

The front bin 17 is in the form of a bottom feed concrete hopper feeding concrete from the bottom thereof in a conventional manner, which is no part of the present invention so need not herein be shown or described further.

Spaced beneath the bin or hopper 17 are the void formers or compacting shoes 15 positioned to extend in the spaces between the reinforcing strands 13, 13 and 14, 14 and suspended from a plate 23 on parallel spaced suspension bars 25, 25. The plate 23 is suspended from beams 26, 26 extending along opposite sides of the frame structure 11 and the' bins 18 and 17 on links 27, 27. As shown in FIGURES 1 and 2, two links 27 are provided at each end of the plate 23. The links 27 extend through blocks 29 and the horizontal legs 30 of longitudinally spaced guide angles 31. The blocks 29 may be welded or otherwise secured to opposite sides of the horizontal legs 30 of the guide angles 32. A resilient ball like bearing member 32, which may be made from rubber or a well known substitute for rubber is supported on the top block 29 and forms a support for an associated link 27 on the hori zontal leg 30 of the guide angle 31. Lock nuts 33 threaded on the upper ends of the links 27, support said links on the resilient balls 32. The lower end of each link 27 extends through a horizontal leg 35 of an angle bracket 37, mounted on and extending upwardly from the base plate 23. A resilient ball-like bearing member 36 is mounted on the underside of the leg 35 and may be like the ball-like bearing member 32. A nut 37 threaded on the lower end of the link 27, retains said link to said ball-like bearing member to suspend the bracket 35 and plate 23 from the horizontal leg 29 of the guide angle 31.

The horizontal leg of the angle bracket slidably engages the inside of the leg of the guide angle 31. The suspension connections of all four links 27 for the plate 23 thus suspend said plate from the frame structure 11 and retain said plate from lateral movement with respect to said frame structure, but accommodate limited longitudinal movement of said plate with respect to said frame structure.

The rearwardly spaced void formers 16 are suspended from a bracket member on longitudinally aligned parallel spaced suspension legs 41, 41. The bracket member 40 may be bolted or otherwise secured at its oppo site ends to parallel spaced channels 41 extending along opposite sides of the frame structure 11 beneath the beams 26, 26. The plane inner faces of the channels 41 may serve as side forms of the slab.

The void formers 16 are similar to the void formers 15 except they are longer than said void formers and have tapered advance ends 43 like the tapered advance ends of the void formers 15, and are hollow inside and are open at their rear end portions. As shown in FIGURE 4, each void former 16 has a bar 44 therein welded in place within the former through a series of holes 45 drilled through the opposite sides of the void former. The bar 44 serves as a base for a vibrator 47. The vibrator 47 is shown as being a high frequency fluid operated vibrator having an intake pipe 49 and an exhaust pipe 50 leading upwardly therefrom. The vibrators 47 may be of a conventional form, one form of commercial vibrator being the USV-25 Vibrolator manufactured by the Martin Engineering Company of Neponset, Ill. The vibrators 47 are all supplied with fluid under pressure such as air, to vibrate the void formers during advance of the frame structure 11 along the floor and follow in the voids formed by the void formers 15, 15, and finish the voids and compact the concrete about the pre-stressed strands or wires 13 and 14 and accommodate the cores (not shown) to be drawn along the voids formed by said void formers in a conventional manner.

It may be seen from FIGURE 3 that the void formers 16, 16 are equally spaced along the bracket 40 on opposite sides of a relatively narrow central void former 51. The void former 51 usually does not contain a vibrator therein and is vibrated by the vibratory action of the vibrators 47, 47 in the void formers 16, 16. Each vibrator 47 is operated at a frequency of from 4,000 to 16,000 vibrations per minute to compact the concrete about the prestressed reinforcing strands and having a greater vibrating effect and giving a better mechanical bond between the reinforcing strands than can be attained by the use of a single vibrator for vibrating all of the void formers.

The front void formers 15, 15 have individual vibrators 55, 55 mounted therein and, like the vibrators 47, 47 are also spaced on opposite sides of a central void former 56, which usually does not have a vibrator therein.

At the rear of the machine above the void formers 16, 16 is a screed 57, which may be suspended from the rear end portion of the machine by links 59. Forwardly of the screed 57 is a series of vibrator shoes 60 placed side by side and having individual vibrators (not shown) thereon, as in an application Ser. No. 214,272 filed Aug. 2, 1962, now Patent No. 3,224,064 issued Dec. 21, 1965 by Robert J. Hummel, Thomas D. Renbert and Howard L. Dennis. The vibrator shoes 60, therefore, need not herein be shown or described in detail.

Forwardly of the vibrator shoes 60 is a vibrator 61 suspended from the frame structure 11 on links 62. The vibrator 61 may have fluid pressure vibrators (not shown) similar to the vibrators 47, mounted adjacent opposite ends thereof. At the discharge end of the center feed bin 18 is a vibrator shoe 63. The vibrator shoe 63 extends across the discharge end of the bin 18 and may be bolted or otherwise secured to the rear end portion of said bin and is bent horizontally to move along the top surface of the concrete discharged by the bin 18. The vibrator 63 mayhave vibrators like the vibrator 47 mounted thereon, for imparting high frequency vibrations to said shoe, and no part of the present invention, so need not herein be shown or described further.

At the extreme forward end of the machine is a strand vibrator 65 for vibrating the top strands 13 and thereby increasing the compaction of the concrete about said strands and preventing slippage of said strands with respect to the concrete slab as the concrete sets. The strand vibrator 65 is shown in FIGURES 5, 6 and 7 as comprising a bar 66, which may be a round bar and has engagement with the top strands 13. The bar 66 has vertically spaced horizontally extending opposite outer end portions 67-having suspension bolts 69, 69 extending upwardly therefrom and welded or otherwise secured thereto. The suspension bolts 69 are shown in FIGURES 1 and 6 as extending through flanges 70, 70 of the beams 26, 26 of the frame structure 11. As shown in these figures, nuts 71 threaded on said suspension bolts abut the undersurfaces of the flanges 70, while nuts and washers'73 retain said suspension bolts to the flanges 70. The bar 66 has a plate 74 mounted thereon and extending along the recessed portion thereof. Vibrators 75, 75 are mounted on said plate, adjacent opposite ends thereof, and extend upwardly therefrom. The vibrators 75 may be high frequency air operated vibrators such as BD19 Vibrolator made by Martin Engineering Company of Neponset, 111., so need not herein be shown or described further. Each vibrator 75 has an intake line 76 leading thereinto and an exhaust line 77 leading therefrom, and connected to a suitable source of air under pressure in a conventional manner.

In operation of the machine, as the machine is moved in the direction of the arrow in FIGURE 1 by its supporting gantry, and assuming the reinforcing strands 13 and 14 are in place and pre-tensioned, the bins 17, 18 and 19 are filled with concrete of the proper consistency. The vibrators 65 engaging the top strands 13 may then be set in operation to set said strands in vibration at the forward end of the machine and vibrate said strands throughout their length. Concrete may then be discharged from the bin 17 onto the pallet 22, and the void formers 15 being set into vibration by the individual vibrators 55 contained therein, will initially compact the concrete about the reinforcing strands 13 and 14 and form rough voids in the concrete. As the machine advances concrete may then be discharged from the bin 18 over the void formers 16, 16which will continue the compacting operation as individually vibrated, and complete the forming of the voids. The vibrator 63 and the links 62 will at the same time compact the concrete about the void formers as they advance and the bin 19 will then discharge concrete on the already compacted concrete to be smoothed by the screed 59, which serves principally to level the concrete and assure a level slab.

It may be seen from the foregoing that an improved form of concrete slab making machine has been provided in which all .of the compacting operations are effected by vibratory movements and that the compaction of the concrete aboutthe strands is enhancedby initially vibrating the top strands in advance of the pouring operation and continuing the .vibration of the top strands for the length thereof as concrete is poured thereon.

It may further be seen that the efficiency in compaction of the concrete is further increased by placing individual vibrators in the void formers and individually vibrating each void former during the entire slab making operation.

The foregoing vibratory operations and particularly the vibration of the top strands and the individual vibration of the void formers more efiiciently compact the concrete around the reinforcing strands and along and over the void formers and the cores drawn thereby,.and obviate false setting .of the concrete with the resultant slipping of the strands, and give a firm mechanical bond around the reinforcing strands, eliminating the strand slippage that has heretofore been prevalent in the manufacture of reinforced concrete slabs, and providing a more dense product.

While I have herein shown and described one form in which the invention may be embodied, it may readily be understood that various variations and modifications in the invention may be attained without departing from the spirit and scope of the novel concepts thereof.

I claim as my invention:

1. In an apparatus for manufacturing concrete slabs having spaced pre-tensioned reinforcing strands extending therealong, a frame mounted for movement along the strands, at least one bin on said frame discharging a layer of concrete over previously pre-tensioned reinforcing strands, vibratory means compacting the concrete about said strands and other vibratory means mounted on and extending transversely of said frame in advance of said bin and engaging the pre-tensioned strands for imparting high frequency vibratory motion to said strands.

2. In an apparatus for manufacturing concrete slabs having spaced pre-tensioned reinforcing strands extending therealong, a frame mounted for movement along the strands, at least one bin on said frame discharging a layer of concrete over previously pre-tensioned reinforcing strands, vibratory means compacting the concrete about said strands and other vibratory means mounted on said frame in advance of said bin for imparting high frequency vibratory motion to said strands, comprising a vibrator suspended from said frame and having engagement with the pre-tensioned strands.

3. An apparatus for manufacturing concrete slabs having spaced pre-tensioned reinforcing strands extending therealong, comprising a frame mounted for movement along the ground, a bin mounted on said frame for discharging a layer of concrete over previously pre-tensioned reinforcing strands, and a vibrator mounted on said frame in advance of said bin and having means associated therewith having vibratory engagement with the pre-tensioned strands.

4. An apparatus for manufacturing concrete slabs having spaced pre-tensioned reinforcing strands extending therealong, comprising a frame mounted for movement along the ground, a bin mounted on said frame for discharging a layer of concrete over previously pre-tensioned reinforcing strands, a member suspended from said frame and extending transversely thereof and positioned to engage the pre-tensioncd strands, and at least one high frequency vibrator on said member for vibrating said member and the strands in advance of said bin.

5. An apparatus for manufacturing concrete slabs having spaced pre-tensioned reinforcing strands extending therealong, comprising a frame mounted for movement along the ground, a bin mounted on said frame for discharging a layer of concrete over previously pre-tensioned reinforcing strands, a member extending transversely of the forward end portion of said frame and suspended therefrom into position to engage the reinforcing strands, and high frequency vibrators at opposite ends of said member imparting high frequency vibratory motion to the reinforcing strands.

6. An apparatus for manufacturing concrete slabs having spaced pre-tensioned reinforcing strands extending therealong, comprising a frame mounted for movement along the ground, a bin mounted on said frame for discharging a layer of concrete over previously pre-tensioned reinforcing strands, a bar extending transversely of said frame, means suspending said bar from said frame into position to engage the pre-tensioned reinforcing strands, a plate extending along said bar, and high frequency vibrators mounted on said plate at opposite ends thereof, for imparting high frequency vibrations to said bar and the pre-tensioned reinforcing strands engaged thereby.

7. In an apparatus for manufacturing concrete slabs having parallel spaced pre-tensioned reinforcing strands extending therealong, a frame mounted for movement along the ground, a vibrator mounted on said frame in advance thereof and having engagement with the pretensioned strands for vibrating said strands, a plurality of void formers disposed rearwardly of said vibrator and suspended from said frame to extend between said strands, and individual vibrators carried by said void formers for individually vibrating said void formers to compact the concrete about said strands, and to form voids in the slab as said frame advances along said pre-tensioned strands.

8. In an apparatus for manufacturing concrete slabs having spaced pre-tensioned strands extending therealon a frame supported for movement along said strands in vertically spaced relation with respect to the ground, first and second vertically extending longitudinally spaced bins mounted on said frame for supplying concrete of different consistencies, a plurality of advance void formers suspended from said frame to extend between said strands and compact the concrete about said strands and form voids therein, a plurality of rearwardly spaced void formers spaced beneath said second bin and extending in alignment with said first void formers for compacting the concrete about said strands and forming voids in the slab, sai-d advance and rearwardly spaced void formers being hollow and having tapered leading ends, and individual vibrators in each of said void formers for imparting vibratory motions thereto and compacting the concrete about said strands and forming voids between said strands, and a vibratory member extending across the forward end portion of said frame and suspended therefrom into position to engage the pre-tension strands, and vibrating means mounted on said member for imparting vibratory motions thereto to set said strands into high frequency vibration.

9. Apparatus according to claim 3, including at least one set of core formers suspended from said frame behind said vibrator.

10. Apparatus according to claim 3, including a plurality of sets of successively operable void formers rearwardly from said vibrator, at least one of said sets of void formers having high frequency vibrating means.

11. Apparatus according to claim 10 in which all of said sets of core formers have vibrators.

12. Apparatus according to claim 3, including in addition core formers associated with said bin, and said core formers being hollow and having therewithin high frequency vibrators.

13. Apparatus according to claim 12, including vibrator means carried by said frame adjacent to but separate'from said core formers.

References Cited UNITED STATES PATENTS 3,060,540 10/ 1962 Lapidus 2541.5 3,143,781 8/ 1964 Kalns 25-41.5 3,177,552 4/1965 Roth et al. 25-41 3,181,222 5/1965 Palmer 2541.5 3,224,064 12/ 1965 Hummel et a1. 2541.1 1,970,740 8/1934 Day 25-41 1,988,315 1/ 1935 Jackson 25-1 2,938,255 5/ 1960 Oakden 25-32 2,962,785 12/ 1960 Young 251 3,123,872 3/1964 Perlmutter et al. 25-118 FOREIGN PATENTS 500,557 7/ 1951 Belgium. 475,341 10/ 1952 Italy.

29,565 7/ 1958 Finland.

1,036,743 8/1958 Germany.

700,569 12/1964 Canada.

I. SPENCER OVERHOLSER, Primary Examiner. 

3. AN APPARATUS FOR MANUFACTURING CONCRETE SLABS HAVING SPACED PRE-TENSIONED REINFORCING STRANDS EXTENDING THEREALONG, COMPRISING A FRAME MOUNTED FOR MOVEMENT ALONG THE GROUND, A BIN MOUNTED ON SAID FRAME FOR DISCHARGING A LAYER OF CONCRETE OVER PREVIOUSLY PRE-TENSIONED REINFORCING STRANDS, AND A VIBRATOR MOUNTED ON SAID FRAME IN ADVANCE OF SAID BIN AND HAVING MEANS ASSOCIATED THEREWITH HAVING VIBRATORY ENGAGEMENT WITH THE PRE-TENSIONED STRANDS. 